Why Do Fat Cells Get Fat? New Suspect Identified

As the world fights obesity at the human level, scientists at the University of Michigan and their colleagues have made a surprising finding at the microscopic level that could help fuel that fight.

Their work helps explain why fat-storing cells get fatter, and burn fat slower, as obesity sets in. If their findings from mice can be shown to apply to humans, they may provide a new target for obesity-fighting drugs.

By studying the tiny signals that fat-storing cells send to one another, the team has shown a crucial and previously unknown role for a molecule called Sfrp5.

The results, which appear online June 25 and will be in the July issue of the Journal of Clinical Investigation, surprised them.

In a series of experiments, the team showed that Sfrp5 influences a signaling pathway known as WNT to stimulate fat cells -- called adipocytes -- to grow larger and to suppress the rate at which fat is burned in the mitochondria inside them.

By stopping cells from making Sfrp5, they were able to make mice that didn't get as fat as quickly because their adipocytes didn't grow large -- even when the mice were fed a high-fat diet. They even showed the impact when transplanting fat from Sfrp5 -- deficient mice into other mice...